In situations where work is being performed in a contaminated environment by workers wearing respirators, they typically exit the contaminated area by passing through one or a series of clean-up areas or decontamination zones. Often the workers continue to wear their respirators in the clean-up areas. This practice, however, presents the risk that contaminated matter, drawn into the filter of the respirator during use, may fall out of the filter in the clean-up area, or even in the clean environment beyond the clean-up area. To avoid this problem, the user of the respirator would sometimes plug up or tape up the filter to prevent contaminants from falling out. In doing this, however, the user blocked the air flow through the filter so that he could no longer use the respirator. As a result, the user would have to remove the respirator at an earlier point in the decontamination process than would otherwise be desirable. Alternatively, the user would, after plugging up the filter, have to hold his breath, until he was sufficiently decontaminated to safely remove the respirator.
U.S. Pat. No. 4,818,122 discloses an accessory device into which is placed the entire filter unit of a respirator so as to permit the user to continue using the respirator while showering. It is primarily designed to keep the filter dry. It consists of a relatively large, flat, triangular-shaped bag made from a waterproof and flexible material. The bag is placed entirely over the filter through a zip-type closure along the entire length of one of the sides of the triangle which is opened to allow placement of the bag therein and then closed to seal the bag around the filter unit with the face mask hose exiting therefrom. Continued use of the respirator is accommodated through a one-way valve located in the side of the bag which allows the in-flow of air to the filter.
One disadvantage of this device is that it cannot be quickly and easily installed since the triangular bag must be carefully positioned so as to align the one-way valve in the bag with the filter inlet of the respirator to prevent the flexible bag from being sucked against the filter. Moreover, even if properly aligned initially, there exists the possibility that the filter inlet and the one-way valve may subsequently become misaligned and cause breathing difficulty for the user.
Another disadvantage of this device is that it is prone to puncture and other damage. Also, it is difficult to clean the device between uses, requiring someone to either reach inside or turn the bag inside out to clean the contaminated matter from the creases along the edges of the triangular bag. Still another disadvantage is that the bag is quite large and bulky since it must accommodate an entire filter unit. Finally, it is questionable whether the zip-type closure cam provide a seal adequate to prevent small diameter particulate matter from passing out of the bag, especially around the location where the face mask hose exits the bag.
It would be desirable, therefore, to provide a small, durable, easy to use, positively sealing device for containing the contaminated matter that falls out of the respirator filter, while at the same time allowing the respirator to continue functioning as the user passes through the various decontamination zones and clean-up areas. Such a device would also allow the respirator to be handled, stored and transported in a clean environment without the necessity of decontaminating it after each use.